Rocky Gorge Upper dam
Rocky Gorge Upper
Rocky Gorge Upper in South Berwick, Maine, is a privately owned hydroelectric dam completed in 1900, standing at a height of 10 feet and a length of 140 feet. With a maximum storage capacity of 141 acre-feet, this concrete gravity dam sits on the Great Works River, with a drainage area of 85.5 square miles. The dam's spillway type is uncontrolled, with a width of 100 feet, and a maximum discharge capacity of 6600 cubic feet per second.
Despite its age, Rocky Gorge Upper has a low hazard potential and a moderate risk assessment rating of 3, as determined by the Federal Energy Regulatory Commission. While the dam has not undergone a recent condition assessment, it has a scheduled inspection frequency of 3 years, with the last inspection conducted in July 2019. The emergency action plan for the dam was last revised in January 2016, ensuring that the necessary protocols are in place in case of any unforeseen events.
With its strategic location and historical significance in the region, Rocky Gorge Upper serves as an essential component of Maine's water resource infrastructure, providing clean hydroelectric power while managing water flow and storage. As a well-maintained and regulated structure under the oversight of federal agencies, the dam continues to play a crucial role in both energy production and environmental stewardship in the area.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Rocky Gorge Upper -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Isinglass R At Rochester Neck Rd | 66 cfs | → |
| Cocheco River Near Rochester | 117 cfs | → |
| Oyster River Near Durham | 13 cfs | → |
| Lamprey River Near Newmarket | 137 cfs | → |
| Winnicut River At Greenland | 22 cfs | → |
| Mousam River Near West Kennebunk | 267 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Rocky Gorge Upper .
Boat launches
- Salmon Falls River Boat Launch
- Dover Eliot Road South Berwick
- Willand Pond Boat Launch
- Piscataqua River Boat Launch
- Cathy Schiro O'Brien Cross Country Running Trail Dover
- Oyster River Boat Launch
Campgrounds
- Old Stage Campground
- Saddleback Campground
- Tidewater Campground
- Remote Campsite
- Ferry Beach Campground
- Salisbury State Park Reservation
Paddle runs
Track Rocky Gorge Upper in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Rocky Gorge Upper
Where does the data for Rocky Gorge Upper come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Low hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Rocky Gorge Upper .